One of the first rules of photography is that the subject should be sharp. Most modern digital cameras offer a number of ways of achieving sharp photos, and in this post we’re going to look at the most important digital camera focus techniques and the best settings to use. We’ll look at how to select the AF point and which focus mode to use.
Although nearly all modern digital cameras can focus the lens automatically (the Leica M9, Leica M9-P and Leica Monochrom being notable exceptions) they also allow you to focus manually instead.
Manual focus is a particularly good option with macro photography because many cameras struggle to lock onto very close subjects and the lens ends up hunting (moving in and out of focus) every time the shutter release button is depressed.
It’s far less frustrating to switch the camera (or the lens) to manual focus and do the job yourself.
What’s more, Live View technology makes manual focusing very easy because it is usually possible to enlarge the image on the screen so that you can see the precise spot that you are interested in, and then adjust the focus until it is perfectly sharp.
Single shot autofocus
Often abbreviated to single autofocus or single AF, this camera focus option sets your camera to focus when the shutter release is depressed half-way and to keep the lens focused on the selected subject until the shot is taken and the button is released.
If you need to refocus you have to lift your finger off the shutter button and then depress it a second time.
Single focus mode is useful for static subjects such a s still life and landscapes.
When this camera focus option is selected the camera will continue to focus the lens as long as the shutter release button is half-pressed, or the AF button is pressed.
This makes it a very good option when photographing moving subjects because the camera will adjust the focus distance as the subject moves.
Advanced cameras such as the Canon EOS 7D and Nikon D7000 have options that enable you to specify which AF points the camera will use to track the subject as it moves about in the frame.
Some even allow you to specify how quickly the camera should respond to changes in subject distance to avoid the subject going out of focus when a stadium pillar, for example, momentarily blocks the view.
When using continuous AF it’s usually best to set the starting AF point manually so the camera knows what the target is before it starts to track it.
If you like shooting sport or fast action then make sure you check out your camera’s continuous AF options.
Automatic focus point selection
When you are focusing automatically you need to have the active AF point over the subject in the viewfinder to get it sharp.
Broadly speaking, there are two ways of selecting the AF point using this camera focus technique.
The easiest is to let your camera decide for you and use the automatic AF selection point option.
In many situations the camera will do a decent job and this is a useful option when you don’t have much time to get the shot.
However, your camera will usually try to focus on the closest object near the centre of the frame and it’s not usually very good at pin-pointing smaller subjects or fine details.
For this reason it’s often better to set the AF point yourself.
Manual AF point selection
Setting the AF point yourself gives you the maximum level of control over where your camera focuses, and it’s a good option for landscape, still life and portrait photography when you have time to operate the necessary camera controls.
Setting this camera focus option is usually done by pressing the AF point selection button and then using the navigation controls to select the AF point you want while you look through the viewfinder.
Once you reach the AF point that is over your subject, you’re ready to focus and take the picture.
In some cases you may be able to set the navigation controls to select the AF point directly without the need to press a button beforehand, but this can be at the expense of their usual shortcut functions.
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